3.1.3《建立表之间的联系》-课后作业 粤教版（2019）-信息技术-数据管理与分析选修3

《建立表之间的联系》作业 一、选择题 1. 在SQL中，以下哪个命令用于创建外键约束？ A. CREATE FOREIGN KEY B. ALTER TABLE ... ADD FOREIGN KEY C. CREATE TABLE ... FOREIGN KEY D. ALTER TABLE ... ADD CONSTRAINT 答案：D 解析：ALTER TABLE ... ADD CONSTRAINT命令用于创建外键约束。外键是一种数据库约束，用于确保一个表中的数据与另一个表中的数据相匹配，以维护数据的一致性和完整性。 2. 在MySQL中，要删除一个外键约束，应使用以下哪个命令？ A. DELETE FOREIGN KEY B. REMOVE FOREIGN KEY C. ALTER TABLE ... DROP FOREIGN KEY D. DROP FOREIGN KEY 答案：C 解析：ALTER TABLE ... DROP FOREIGN KEY命令用于删除MySQL中的外键约束。执行此操作后，外键约束将被移除，但相关的数据列仍然存在。 3. 在PostgreSQL中，要创建一个名为“fk_department_id”的外键约束，引用“departments”表中的“id”列，应使用以下哪个语法？ A. ALTER TABLE employees ADD CONSTRAINT fk_department_id FOREIGN KEY (department_id) REFERENCES departments(id); B. ALTER TABLE employees ADD fk_department_id FOREIGN KEY (department_id) REFERENCES departments(id); C. ALTER TABLE employees ADD CONSTRAINT fk_department_id FOREIGN KEY (id) REFERENCES departments(department_id); D. ALTER TABLE employees ADD CONSTRAINT fk_department_id FOREIGN KEY (department_id) REFERENCES departments(department_id); 答案：A 解析：正确的语法是ALTER TABLE employees ADD CONSTRAINT fk_department_id FOREIGN KEY (department_id) REFERENCES departments(id);。这会创建一个名为“fk_department_id”的外键约束，确保“employees”表中的“department_id”列引用“departments”表中的“id”列。 4. 在SQL Server中，要创建一个名为“FK_Employee_Department”的外键约束，引用“Departments”表中的“DepartmentID”列，应使用以下哪个语法？ A. ALTER TABLE Employees ADD CONSTRAINT FK_Employee_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(DepartmentID); B. ALTER TABLE Employees ADD FK_Employee_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(DepartmentID); C. ALTER TABLE Employees ADD CONSTRAINT FK_Employee_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(DepartmentID); D. ALTER TABLE Employees ADD FK_Employee_Department FOREIGN KEY (EmployeeID) REFERENCES Departments(DepartmentID); 答案：C 解析：正确的语法是ALTER TABLE Employees ADD CONSTRAINT FK_Employee_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(DepartmentID);。这会创建一个名为“FK_Employee_Department”的外键约束，确保“Employees”表中的“DepartmentID”列引用“Departments”表中的“DepartmentID”列。 5. 在Oracle数据库中，要创建一个名为“FK_EMP_DEPT”的外键约束，引用“DEPARTMENTS”表中的“DEPT_ID”列，应使用以下哪个语法？ A. ALTER TABLE EMPLOYEES ADD CONSTRAINT FK_EMP_DEPT FOREIGN KEY (DEPT_ID) REFERENCES DEPARTMENTS(DEPT_ID); B. ALTER TABLE EMPLOYEES ADD FK_EMP_DEPT FOREIGN KEY (DEPT_ID) REFERENCES DEPARTMENTS(DEPT_ID); C. ALTER TABLE EMPLOYEES ADD CONSTRAINT FK_EMP_DEPT FOREIGN KEY (EMP_DEPT) REFERENCES DEPARTMENTS(DEPT_ID); D. ALTER TABLE EMPLOYEES ADD CONSTRAINT FK_EMP_DEPT FOREIGN KEY (EMP_ID) REFERENCES DEPARTMENTS(DEPT_ID); 答案：A 解析：正确的语法是ALTER TABLE EMPLOYEES AD ... ...